1. Technical Field
The present application relates to a technique of recording data to be used for the adjustment of a hearing aid. More specifically, the present application relates to an apparatus, method, and program for recording, together with sounds which a user may hear in various acoustic environments in daily life, electroencephalogram data which reflects states of hearing with respect to such sounds.
2. Description of the Related Art
In recent years, due to the aging society, increased opportunities for listening to loud music for long hours, and other influences, there is an increasing number of people suffering from presbycusis or hypacusia associated with acoustic traumas. Moreover, due to the downsizing and improved performance of hearing aids, users feel less of a psychological barrier against wearing hearing aids, and there is an increasing number of users who use hearing aids for the purpose of improving aural comprehension of daily conversations.
A hearing aid is a device for compensating for the deteriorated hearing ability of a user by increasing the amplitude of signals of specific frequencies, among various frequencies that compose sounds that are difficult for the user to hear. The amount of sound amplification which a user desires in a hearing aid varies depending on the level of deterioration in the hearing ability of the user, and also on the frequency band. Therefore, before beginning use of a hearing aid, a “fitting” is required for adjusting the amount of sound amplification for each frequency, in accordance with the hearing ability of each user.
Fitting is performed in order to ensure that the output sound pressure (i.e. fluctuations in air pressure that are perceivable as a sound) of each frequency from a hearing aid is at an MCL (most comfortable level: a sound pressure that is felt comfortable to a user).
In a first step of fitting, an audiogram is measured. An “audiogram” is a result of hearing assessment with respect to pure tones of different frequencies, performed at a hearing aid shop or hospital first, i.e., a result of assessing a hearing threshold value defining a smallest sound pressure of a pure tone that allows it to be heard. For example, an “audiogram” may be in the form of a diagram in which, for each of a number of sounds of different frequencies, the smallest sound pressure level (decibel value) that the user can aurally comprehend is plotted against frequency (e.g., 250 Hz, 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz).
Then, from the audiogram, an initial adjustment is performed to determine an amount of amplification based on a fitting technique, which is a method of adjustment for providing amplification to a sound pressure level for attaining comfortable hearing. As necessary, a hearing aid shop further performs a speech sound intelligibility assessment, which involves presenting monosyllabic audios one by one to the user orally or from a sound source such as a CD, and making assessments as to whether the speech sounds were actually aurally comprehended, and thus makes a fine adjustment for the hearing aid. Through repetitions of such assessments and hearing aid adjustments, a hearing aid is obtained which has characteristics suited to the hearing of the user.
However, there has been a problem in that satisfactory adjustments for a hearing aid may not necessarily be made even through such fully-attended adjustments, because such hearing aid assessments and adjustments are made in a hearing aid shop and by a shop expert.
It is in the scenes of daily life that a user of a hearing aid actually wears the hearing aid, e.g., in the household, while watching television, or while going out. The optimum values of adjustment for the hearing aid will presumably differ from situation to situation. Conventionally, when any dissatisfaction with regard to the adjustment of a hearing aid is felt in the daily life, such scenes of dissatisfaction must be memorized, and conveyed to an expert. For example: there are no problems with conversations but television tends to sound too loud; while there are no problems conversing with an expert at the hearing aid shop, talking to the family still presents difficulties in hearing; and so on. As the hearing aid user conveys the dissatisfaction to the expert at the hearing aid shop, the expert makes a readjustment based on that result.
The difficulty in such adjustments is that the user needs to recall from memory those past experiences of difficulty of hearing, and try to explain the particular scene(s) and difficulty of hearing to the expert, who tries to estimate from the user's report what sort of difficulty of hearing was felt by the user in what sort of acoustic environment, and make a readjustment for the hearing aid. In the first place, subjective expressions of hearing may permit a lot of variations, and the difficulty of adjustments is further enhanced by reliance on memory.
This problem may be addressed by an approach of automatically recording the acoustic environments and states of hearing in scenes of daily life, this recorded data being acquired by an expert of a hearing aid shop either at the shopfront or via remote control, who analyzes the content of the data so that it is utilized as information for hearing aid fitting.
Conventional techniques related to this approach are as follows. Japanese National Phase PCT Laid-Open Publication No. 2009-512376 (hereinafter “Patent Document 1”) discloses a hearing aid that has a data logger which logs the data of an input signal (ambient sound), and records results of characteristic analysis of parameters. This permits a quantitative understanding of what sort of acoustic environment(s) the user has been living in.
Japanese National Phase PCT Laid-Open Publication No. 2010-525696 (hereinafter “Patent Document 2”) discloses a user-specific fitting method which, after an initial fitting is made, monitors and records a log of a history of choices made by a hearing aid user from among a set of plural gain parameters (i.e., a history of control operations made on the hearing aid), so that an expert at a hearing aid shop is able to determine from the log a final setting value for the hearing aid. This approach indirectly estimates the acoustic environment and state of hearing of the user by relying on the history information concerning which one of a set of plural gain parameters belonging to the hearing aid has been used most frequently.
Japanese Laid-Open Patent Publication No. 2010-4432 (hereinafter “Patent Document 3”) discloses a hearing aid which, in response to each press of a store button by the user whenever feeling uncomfortable, records an ambient sound existing at that point in time, so that this stored sound is reproduced at the time of fitting for facilitating the fitting. Thus, the user is allowed to again hear at the hearing aid shop a sound which was difficult to aurally comprehend, etc., whereby the user is able to remember the scene which presented hearing difficulty. These techniques are all aimed at recording situations in scenes of daily life, with a view to realizing a more appropriate hearing aid fitting.